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Aldabra Atoll contributes to first scientific report on blue carbon in marine world heritage sites |03 March 2021

New research demonstrates the crucial role of world heritage marine sites in fighting climate change.

On February 25, 2021 the United Nations Educational, Scientific and Cultural Organisation (Unesco) released the first global scientific assessment of its world heritage marine sites’ blue carbon ecosystems, highlighting the critical environmental value of these habitats. While these sites represent less than 1% of the world’s oceans, they host at least 21% of the world’s blue carbon ecosystem area, and 15% of the world’s blue carbon assets.

A press conference to present the findings of the new report, Unesco Marine World Heritage – Custodians of the Globes Blue Carbon Assets, took place online yesterday. During the press conference, lead author, Professor Carlos Duarte of the King Abdullah University of Science and Technology in Saudi Arabia, and Dr Fanny Douvere of Unescco’s Marine World Heritage Programme, explained that marine world heritage carbon stores were equivalent to about 10% of the world’s annual greenhouse gas emissions in 2018, safely keeping billions of tons of CO2 and other greenhouse gases out of the atmosphere. Published at the start of the United Nations Decade of Ocean Science for Sustainable Development, the assessment also points to ways to preserve these invaluable sites.

“Found on the fringes of the world’s coastlines, blue carbon ecosystems play an important ecological role in nutrient and carbon cycling, as nurseries and habitats for a broad range of marine and terrestrial species, in shoreline protection, and in sustaining the livelihoods and well-being of local communities” Ernesto Ottone R., Unesco assistantdirector-general for culture.

Over the last decade, scientists have discovered that seagrass meadows, tidal marshes, and mangroves, known as “blue carbon” ecosystems, are among the most intensive 'carbon sinks', meaning a natural environment which can absorb carbon dioxide in the biosphere. They help mitigate climate change by sequestering and storing significant amounts of carbon from the atmosphere and ocean.

Unesco world heritage sites are places of outstanding universal value, recognised by the international community as needing to be safeguarded for future generations. The report demonstrates that Unesco marine world heritage sites act as custodians of the largest blue carbon ecosystems in the world, making them more valuable than ever. Collectively, marine worldheritage ecosystems encompass an area of 207 million hectares, representing 10% of all protected marine area globally, as of 2020.

They include Sundarbans mangroves (India and Bangladesh), part of the largest mangrove forest in the world; the Everglades National Park (USA) and Shark Bay, Western Australia (Australia), with the world’s largest documented seagrass meadows; the Great Barrier Reef, with the largest seagrass ecosystem in the world; and the Wadden Sea (Denmark, Germany, the Netherlands), which includes some of the world’s largest tidal flats. Marine world heritage sites also host one of the oldest and largest living organisms on the planet, the seagrass meadows of Ibiza, Biodiversity and Culture (Spain).

Seychelles’ very own Aldabra atoll, with a total a seagrass area of 7,540 hectares (ha) and mangrove area of 1,700 ha is understood as having a total blue carbon ecosystem area of 9,240ha and total blue carbon ecosystem C stock of 1,041,006 megagrams (Mg C).

Commenting on the report, Seychelles Islands Foundation’s (SIF) chief executive Dr Frauke Fleischer-Dogley stated: “This assessment highlights the enormous conservational value as well as spill over effects of Unesco world heritage sites at global and national levels. Specifically, here in Seychelles, Aldabra’s highly effective management has convinced all stakeholders of the Marine Spatial Plan initiative and led to an extension and new designation of a large non-take protected area around it that is 575 times the original size of the Aldabra atoll special reserve. This is equal to the size of Senegal. I believe this report will serve as a catalyst in better appreciating and protecting other protected areas in Seychelles as well as around the world.”

The 50 Unesco marine world heritage sites that harbour unique collection of marine ecosystems face a wide range of challenges, from pollution, including plastic litter, to climate change. By quantifying the carbon value of these sites and recommending specific blue carbon strategies to conserve them, Unesco’s research findings point the way for countries, regions, and local communities seeking to conserve these areas and pursue blue carbon strategies.

“Because they store so much carbon, blue carbon ecosystems become sources of CO2 emissions when they are degraded or destroyed. Protection and restoration of these ecosystems present a unique opportunity to mitigate climate change. By conserving blue carbon ecosystems, the large carbon stocks they have accumulated over millennia can be protected. As they are restored, they can regain their function as carbon sinks,” said Professor Calos M. Duarte.

Conservation funding for blue carbon ecosystems in marine world heritage sites could be boosted through blue carbon strategies, whereby countries would earn carbon credits for demonstrating carbon benefits from the restoration and conservation of damaged ecosystems. Blue carbon strategies can restore vital ecosystem services and crucially help nations deliver on their commitments under the Paris Climate Agreement. To date, however, a limited number of countries have incorporated blue carbon strategies into their climate change mitigation policies.

The assessment was developed with data from world heritage site managers, data published in scientific literature and The Global Carbon Project’s Global Carbon Atlas. It received support from King Abdullah University of Science and Technology (Saudi Arabia), the French Biodiversity Agency and the Principality of Monaco.


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